In general, a smart card includes a contact-type integrated circuit (IC) card in which the data is transmitted and received via contacts exposed on a card surface, and a noncontact-type radio frequency (RF) card in which a built-in antenna coil deals with the data wirelessly.
In recent days, there is a need for a combi-card (combinational card), which can be used for both contact-type and noncontact-type because of its convenient usability and compatibility. The combi-card is provided with both the contacts of the contact-type IC card and the antenna coil of the noncontact-type RF card.
Typically, the combi-card is made of a transparent or opaque synthetic resin sheet such as PVC, ABS, PC, PETG, PET, etc. In the conventional combi-card, a lower protection layer 10, a lower printing layer 20, an antenna coil insertion layer 30 at which an antenna coil is inserted, an upper printing layer 40, and an upper protection layer 50 are sequentially stacked from the lower to the upper surface.
FIG. 1 shows a process for making the conventional combi-card.
As shown in FIG. 1, an antenna coil 31 is first wound along the edge of the antenna coil insertion layer 30, and an antenna terminal 34, which is connected with the antenna coil, is formed on a part of the antenna coil.
After the antenna terminal 34 has been formed, the lower protection layer 10, the lower printing layer 20, the antenna coil insertion layer 30, the upper printing layer 40, and the upper protection layer 50 are sequentially stacked, and then they are heat-pressed, and cut out, to thereby form a layered card body 70.
After the card body 70 has been constructed, an opening 72 is formed at the place where the antenna terminal 34 is located on the card body 70. Thereafter, a conductive viscous adhesive 108 is coated on the antenna terminal 34 exposed to the outside through the opening 72, and then a rectangular COB (Chip on Board) 100, on which an IC chip and its contacts are mounted, is inserted into the opening 72.
After the COB 100 has been inserted into the opening 72, heat and pressure is applied onto the COB 100 so that a Hot-Melt tape 111 which has been treated on the COB 100 is adhered to the card body 70. Simultaneously, as the conductive adhesive 108 is hardened, the antenna terminal 34 of the antenna coil and the contacts 104 of the COB 100 are electrically connected to one another. As a result, a complete combi-card is produced.
However, in the above conventional method, there arises a problem in that, if the bending or torsional force is applied to the combi-card, a crack occurs in the interface of the conductive adhesive 108 and so the contact failure is arisen between the contacts 104 of the COB and the antenna terminal 34 of the card body 70. This is because elongation and modulus of elasticity of material constituting the card, and adhesion of the Hot-Melt tape 111 or the thermosetting adhesive which is used to attach the COB 100 to the card body 70 are insufficient. In addition, this is due to the difference of the physical properties between the antenna terminal 34 and the conductive adhesive 108 which establishes an electrical connection between the antenna terminal 34 and COB contacts 104.
This is the structural problem arisen from a conventional combi-card manufacturing process. The antenna terminal 34, which is embedded in the card body 70, is affected by the physical properties of the card body 70, such as elongation, modulus of elasticity and the like. Also, the COB contacts 104 are affected by the physical property of the base layer 103 of the COB 100. Since the adhesive strength of the Hot-Melt tape 111 or the thermosetting adhesive connecting the two layers is insufficient, and the combi-card deteriorates in its function by aging and fatigue of the conductive adhesive 108, a lot of defective products are created.
Korea Patent No. 10-385660 (issued on May 16, 2003) invented to overcome such problems, discloses a combi-card manufacturing method in which the exterior of the IC chip module is designed largely enough to be built-in the card body, and a stacked sheet suitable for the IC chip module is included therein.
However, in such a prior art, although the IC chip module embedded in the card body effectively, it is necessary that the design and manufacturing of the IC chip module should be specially performed, and all kinds of facilities relating to the IC chip module must be specially fabricated. In addition, since the IC chip module is not adhered by an adhesive, the durability becomes decreased and the manufacturing costs increase.